1. Field of the Invention
The present invention relates to a video signal recording and reproducing apparatus for a digital video cassette tape recorder (DVCR), and particularly to an improved video signal recording and reproducing apparatus for a DVCR which is capable of dividing, recording and reproducing a digital signal outputted from the same source onto multiple tracks based on the amount of data recorded on one track by controlling a recording/reproducing speed and a tape running speed in accordance with a judgement result after judging the type of video tape having a predetermined recordable wavelength.
2. Description of the Conventional Art
Generally, a digital video cassette tape recorder (DVCR) is directed to recording a digital signal from a digital broadcast source such as an advanced television system, a cable TV decoder, or a satellite broadcast signal receiver onto a video tape which is referred to as a magnetic recording medium and to reproducing the recorded digital signal.
The DVCR includes an integrated receiver decoder (IRD), which is referred to as an exclusive receiver, for receiving the digital signal broadcast from the digital broadcast source, and thus recording the received digital signal onto a video tape using a video signal processing means, and for reproducing the recorded digital signal.
In addition, a digital VHS VCR (DVHS-VCR) is directed to recording digital signals onto a video tape in a recording pattern as shown in FIG. 1 and reproducing the recorded digital signals.
Here, one track on the tape includes a first preamble data region which is recorded at the start portion of each track and indicates the start of the track, a sub-code region contains certain information referred to for a recording/reproducing operation, a main data region which contains a video information, and a second preamble data region which is recorded at the end portion of each track and indicates the end of the track.
The above-mentioned digital signal is received through the IRD (not shown). A format unit formats the video signal. A signal processor modulates the signal, and then the signal is recorded onto the video tape in the pattern as shown in FIG. 1. The signal reproduced from the video tape is demodulated by the signal processor, and de-formatted by the format unit and then is outputted. Here, the rotation speed of a head drum in the recording/reproducing mode is 1800 rpm which is the same as in the conventional VHS format mode.
Here, the digital tape, that is, a super VHS (SVHS) tape, is generally used, which has a recording wavelength of 0.8 .mu.m rather than 1.4 .mu.m of the normal VHS tape so as to more effectively record/reproduce more digital information thereon without recording/reproducing loss and noise as compared with an analog video signal.
FIG. 2 shows a video signal recording/reproducing apparatus of a conventional DVHS VCR, which includes an input/output unit 10 connected to an IRD for receiving a digital signal and for outputting a reproduced digital signal, a format formation unit 11 including a data formatter unit 11a connected to the input/output unit 10 for formatting an error correction code of the data and a tape recording formatter unit 11b connected to the data formatter unit 11a for forming the formatted data into a recording format on the video tape, a recording/reproducing signal processor 12 connected to the format formation unit 11 for performing the record signal processing and the reproduce signal processing including modulation and demodulation of the digital signal, a head drum 13 provided with a video head 14a for recording the recording signal outputted from the recording/reproducing signal processor 12 onto the video tape 13, and for reproducing the digital signal recorded on the video tape 13 and outputting the reproduced signal to the recording/reproducing signal processor 12, a servo controller 15 for controlling the running of the video tape 13 and the rotation of the head drum 14, a clock generator 16 for outputting a format clock signal to the format formation unit 11, and a clock signal, which is necessary to record and reproduce the digital signal, to the recording/reproducing signal processor 12, and a reference clock signal to the servo control to the servo controller 15, and a system controller 17 for controlling the data formatting process of the format formation unit 11 and the operation of the servo controller 15.
The operation of the video signal recording/reproducing apparatus of a conventional DVHS VCR will now be explained with reference to FIG. 2.
To begin with, the operation of the video signal recording and reproducing apparatus in the recording mode will first be explained.
The digital signal transmitted from the digital broadcast source is received through the IRD (not shown), and then inputted to the data formatter unit 11a of the format formation unit 11 through the input/output unit 10.
The data formatter unit 11a corrects the errors in the inputted digital signal, generates an additional information (a sub-code) to be recorded as shown in FIG. 1, and then outputs the data to the tape recording formatter unit 11b, and the tape recording format for unit 11b changes the inputted digital signal into a pattern to be recorded on the video tape 13, generates the recording timing and then outputs the signal to the recording/reproducing signal processor 14.
Here, the format formation unit 11 receives the clock signal, which is necessary to form a format, from the clock generator 16 and a driving clock signal and a control signal (generation and reading of an additional data) from the system controller 17, performs a data process, and then outputs the formatted digital video signal to the recording/reproducing signal processor 12. The recording/reproducing signal processor 12 performs a record processing of the digital signal inputted thereto in accordance with the recording clock signal outputted from the clock generator 16 and transmits the processed signal to the video head 14a of the head drum 14.
The servo controller 15 controls the running of the video tape 13 and the rotation of the head drum 14. In the case of the DVHS VCR, the head drum 14 is rotated at 1800 rpm like in the VHS VCR. The digital signal is recorded on the S-VHS tape 13 in the pattern as shown in FIG. 1.
The operation of the video signal recording/reproducing apparatus of the DVHS VCR as shown in FIG. 2 in the reproducing mode is performed in reversed order to the recording mode.
That is, the video tape 13 is normally transported in accordance with a control of the servo controller 15. The head drum 14 is rotated at 1800 rpm, and the digital signal recorded on the video tape 13 is reproduced in cooperation with the video head 14a.
The reproduced recorded digital signal is reproduce-processed by the recording/reproducing signal processor 12, and then is demodulated by the tape recording formatter unit 11b. The errors in the signal are corrected by the data formatter unit 11a, and then the error corrected reproduced signal is outputted through the input/output unit 10.
However, as shown in FIG. 1, since the recording pattern of the video signal recording/reproducing apparatus of the conventional DVHS VCR is completely different from the recording pattern for an analog video signal, a high density recording/reproducing tape must be exclusively used.
When recording/reproducing a digital video broadcast using the DVHS VCR, since it is only possible to record/reproduce the high density using the SVHS tape, the recording density becomes lowered when using a normal tape for recording/reproducing the analog signal, so that the effective recording/reproducing of the digital signal is difficult.
The recording density difference is related to the recording wavelength of the tape. Generally, in the case of the normal video tape, the effective recording wavelength is about 1.4 .mu.m, and the effective recording wavelength of the SVHS tape is about 0.8 .mu.m.
Therefore, as shown in FIG. 1, when recording digital data outputted from the same source, it is possible to record as much as one track on the high density SVHS tape having an effective wavelength of 0.8 .mu.m. In case of the low density VHS tape having an effective wavelength of about 1.4 .mu.m, since the recording wavelength is longer, and the region on which the data is recorded is limited, and it is impossible to record as much digital data as one track on the tape.
That is, in the conventional art, a high density video tape must be used for recording and reproducing the digital signal.
In addition, the video tape widely used with the analog VCR can not be used for recording and reproducing the digital signal.
When a user reproduces a digital video signal using the normal video tape in the DVHS VCR after recording the signal in the DVHS VCR, and a desired picture is not displayed, the user may think there is operational error in the VCR or video tape. So as to overcome the above-mentioned problems, when the DVHS VCR is equipped with a VHS recording failure apparatus, the user may think there are operational problems when the signal recorded on the normal video tape is not displayed. That is, the user should carefully operate the system.